November 22nd, 2016

Widespread, Thick Water Ice found in Utopia Planitia, Mars

This vertically exaggerated view shows scalloped depressions in a part of Mars where such textures prompted researchers to check for buried ice, using ground-penetrating radar aboard NASA's Mars Reconnaissance Orbiter. Image Credit: NASA/JPL-Caltech/Univ. of Arizona

This vertically exaggerated view shows scalloped depressions in a part of Mars where such textures prompted researchers to check for buried ice, using ground-penetrating radar aboard NASA’s Mars Reconnaissance Orbiter. Image Credit: NASA/JPL-Caltech/Univ. of Arizona

My paper on the discovery of a widespread (~375 000 sq km) subsurface water ice deposit in southwestern Utopia Planitia, Mars, was published in Geophysical Research Letters (GRL) a few weeks back, along with a NASA press release today. The detailed version is offered in the journal article, but I thought I’d include a higher-level description of what’s up in here.

When you look at Utopia Planitia, there’s a lot of weird stuff going on. For those that aren’t intimately familiar with martian geography, Utopia Planitia is a huge, ~3300 km diameter basin that formed by impact early in Mars’ history. It makes up part of what’s known as the northern plains, the more-or-less flat terrain north of the martian dichotomy boundary. For as long as we’ve had good imagery from the region, we’ve noticed interesting features on the surface—features like polygonal cracked terrain and oddly-shaped, rimless pits called “scalloped depressions”. When we see features like this on Earth, they’re associated with subsurface ice or permafrost. These features led scientists to believe that this is an ice-rich region of Mars, and inspired my team to examine radar sounding data from the area.

November 21st, 2016

How bad is the radiation on Mars?

Diagram showing the amount of cosmic radiation the surface of Mars is exposed to. Credit: NASA

Diagram showing the amount of cosmic radiation the surface of Mars is exposed to. Credit: NASA

Mars has no protective magnetosphere, as Earth does. Scientists believe that at one time, Mars also experienced convection currents in its core, creating a dynamo effect that powered a planetary magnetic field. However, roughly 4.2 billions year ago – either due to a massive impact from a large object, or rapid cooling in its core – this dynamo effect ceased.

As a result, over the course of the next 500 million years, Mars atmosphere was slowly stripped away by solar wind. Between the loss of its magnetic field and its atmosphere, the surface of Mars is exposed to much higher levels of radiation than Earth. And in addition to regular exposure to cosmic rays and solar wind, it receives occasional lethal blasts that occur with strong solar flares.

November 8th, 2016

Capturing Martian Weather in Motion

Dust stom over Tempe Terra, Mars ESA / DLR / FU Berlin (G. Neukum) / Justin Cowart

Dust stom over Tempe Terra, Mars
ESA / DLR / FU Berlin (G. Neukum) / Justin Cowart

Still images of Mars often give us a false impression that Mars is a dead planet, with nothing going on other than the occasional dust storm. Do a quick image search for Mars and most of the results are mosaics designed to show Martian geography, not meteorology. But these images don’t tell the planet’s full story. Martian weather is dynamic, with water ice cloud streets forming around the polar areas, cold fronts pushing through the midlatitudes and raising dust storms, and thin hazes forming as air flows around topographic obstacles like volcanoes and crater rims.

No space agency has deployed a dedicated weather satellite to Mars, so we can’t watch these systems form and move across the surface like we can with the spectacular images of Earth returned by satellites like Himawari-8. In fact, the only instrument dedicated to monitoring Martian weather, the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter, can only image a location on the Martian surface once per day (with the exception of some areas near the poles).

Fortunately for Martian weather enthusiasts, there is a way to get a glimpse of weather in action at the Martian surface. The High Resolution Stereo Colour Imager (HRSC) instrument onboard Mars Express was designed to produce stereographic color maps of Mars. To do this, HRSC uses a set of 9 pushbroom sensors. Four of these sensors image the surface in color at blue, green, red, and near-IR wavelengths. The other five collect stereo and photometric data using broadband filters that cover the same roughly the same spectral range. The sensors are mounted at different angles, looking between 20 degrees ahead and behind the spacecraft. Parallax from the five different viewing angles allows mission scientists to create DEMs of the surface with 10 to 15 meter vertical resolution.

That’s the intended purpose, anyway. The offset viewing angles for the sensors onboard the spacecraft allow for something else: time-lapse images. The imaging setup means that the first imaging channel sees the surface about 70 seconds before the last. If the wind is blowing at the surface, the time between sequential images is just long enough that the motion of dust clouds is visible. If clouds are at higher altitude, then the parallax also shows up as motion. The color data can then be overlain to colorize the scene.

November 3rd, 2016

Egg Rock: Lessons from the iron meteorite Curiosity found on Mars

The dark, smooth-surfaced rock at the center of this Oct. 30, 2016, image from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover was examined with laser pulses and confirmed to be an iron-nickel meteorite. It is about the size of a golf ball. Credit: NASA/JPL-Caltech/MSSS

The dark, smooth-surfaced rock at the center of this Oct. 30, 2016, image from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover was examined with laser pulses and confirmed to be an iron-nickel meteorite. It is about the size of a golf ball. Credit: NASA/JPL-Caltech/MSSS

It’s been more than four years since NASA’s Curiosity rover landed on Mars, enabling researchers to study the shape and composition of the planet’s landscape in a mission that had originally been planned to last less than two years. Even as the rover’s instruments begin to show signs of wear and tear, however, scientists are still making discoveries.

For the first time on Mars, researchers used a spectrometer to zap an object the size of a golfball with a laser this week to confirm that it is an iron-nickel meteorite that fell to the planet’s surface, according to NASA and the Jet Propulsion Laboratory. Although such objects are common on Earth and to be expected on the Red Planet as well, studying them in tandem with what we already know about the planet’s atmosphere could reveal a wealth of new information about the history of the solar system.

Horton Newsom, a researcher from the University of New Mexico, Albuquerque, said the object, known as Egg Rock, could carry within its core information that differs from asteroids currently being studied.

October 18th, 2016

MAVEN Gives Unprecedented Ultraviolet View of Mars

New global images of Mars from the MAVEN mission show the ultraviolet glow from the Martian atmosphere in unprecedented detail, revealing dynamic, previously invisible behavior. They include the first images of “nightglow” that can be used to show how winds circulate at high altitudes. Additionally, dayside ultraviolet imagery from the spacecraft shows how ozone amounts change over the seasons and how afternoon clouds form over giant Martian volcanoes. The images were taken by the MAVEN Imaging UltraViolet Spectrograph (IUVS).

“MAVEN obtained hundreds of such images in recent months, giving some of the best high-resolution ultraviolet coverage of Mars ever obtained,” said Nick Schneider of the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. Schneider is presenting these results Oct. 19 at the American Astronomical Society Division for Planetary Sciences meeting in Pasadena, California.

September 16th, 2016

Mars had liquid water a billion years longer than we even thought possible

Valleys much younger than well-known ancient valley networks on Mars are evident near the informally named “Heart Lake” on Mars. This map presents color-coded topographical information overlaid onto a photo mosaic. Lower elevations are indicated with white and purple; higher elevations, yellow.
Credits: NASA/JPL-Caltech/ASU

Lakes and snowmelt-fed streams on Mars formed much later than previously thought possible, according to new findings using data primarily from NASA’s Mars Reconnaissance Orbiter.

The recently discovered lakes and streams appeared roughly a billion years after a well-documented, earlier era of wet conditions on ancient Mars. These results provide insight into the climate history of the Red Planet and suggest the surface conditions at this later time may also have been suitable for microbial life.

“We discovered valleys that carried water into lake basins,” said Sharon Wilson of the Smithsonian Institution, Washington, and the University of Virginia, Charlottesville. “Several lake basins filled and overflowed, indicating there was a considerable amount of water on the landscape during this time.”

Wilson and colleagues found evidence of these features in Mars’ northern Arabia Terra region by analyzing images from the Context Camera and High Resolution Imaging Science Experiment camera on the Mars Reconnaissance Orbiter and additional data from NASA’s Mars Global Surveyor and the European Space Agency’s Mars Express.

September 13th, 2016

Mars Rover Views Spectacular Layered Rock Formations

This view from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover shows a hillside outcrop with layered rocks within the “Murray Buttes” region on lower Mount Sharp.

The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA’s Curiosity Mars rover, which is currently exploring the “Murray Buttes” region of lower Mount Sharp. The new images arguably rival photos taken in U.S. National Parks.

Curiosity took the images with its Mast Camera (Mastcam) on Sept. 8. The rover team plans to assemble several large, color mosaics from the multitude of images taken at this location in the near future.

“Curiosity’s science team has been just thrilled to go on this road trip through a bit of the American desert Southwest on Mars,” said Curiosity Project Scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory, Pasadena, California.

August 17th, 2016

Gullies on Mars: Wet or Dry (Ice)?

Martian gullies were in the spotlight recently thanks to a NASA press release stating they were “likely not formed by liquid water.” The release concerns the publication of a new paper by Nuñez et al. in Geophysical Research Letters, which looked at spectral data of gullies from the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).

In their study, Nuñez and his colleagues looked at over 100 gullied locations on Mars. They found no evidence of minerals that would be expected to form in the presence of water. Rather than water, they point to sublimation of seasonal carbon dioxide frost as the main culprit behind gully formation on Mars. Other people have proposed a similar model to explain present-day activity in gullies, which appears to happen during periods of active defrosting. But this process has been a topic of debate among the Mars gullies community, and was a big discussion point at the “Martian Gullies and Their Earth Analogues” workshop in London back in June. Can this dry process explain both the initial formation of gullies and gullies’ modern-day activity?

May 15th, 2016

The seasons on Mars: NASA’s Curiosity rover paints a picture

NASA’s Curiosity rover completed its second Martian year – 687 Earth days – on May 11, meaning that its instruments have now tasted the red planet’s tendencies for two full orbits of the sun.

This allows scientists to begin separating unique events from those that recur year by year, laying the foundation for an understanding of seasonal variations in a host of different characteristics.

The fresh insights come at a time when talk of a manned mission to Mars is edging away from the arena of science fiction and towards the realm of human endeavor.

March 24th, 2016

NASA gravity map offers closest ever look at Mars

By tracking the gravitational pull on spacecraft over Mars, NASA has created one of the most detailed maps yet of the Red Planet’s surface, and what lies beneath.

“Gravity maps allow us to see inside a planet, just as a doctor uses an X-ray to see inside a patient,” Antonio Genova of the Massachusetts Institute of Technology (MIT) said in a statement.
“The new gravity map will be helpful for future Mars exploration, because better knowledge of the planet’s gravity anomalies helps mission controllers insert spacecraft more precisely into orbit about Mars.”
As well as providing insight for future missions, the gravity map also offers explanations for developments in the planet’s past.